Replace deprecated base::NonThreadSafe in google_apis/gaia in favor of SequenceChecker.

google_apis/gaia/oauth2_token_service_request.h

Index: google_apis/gaia/oauth2_token_service_request.h
diff --git a/google_apis/gaia/oauth2_token_service_request.h b/google_apis/gaia/oauth2_token_service_request.h
index 4f2884720467bde94aab75e8f4472b6c639327ca..1ce03258dbc5784cc772e9d02a1ddbba04deec65 100644
--- a/google_apis/gaia/oauth2_token_service_request.h
+++ b/google_apis/gaia/oauth2_token_service_request.h
@@ -11,16 +11,15 @@
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
+#include "base/sequence_checker.h"
 #include "base/single_thread_task_runner.h"
-#include "base/threading/non_thread_safe.h"
 #include "google_apis/gaia/oauth2_token_service.h"
 
 // OAuth2TokenServiceRequest represents an asynchronous request to an
 // OAuth2TokenService that may live in another thread.
 //
 // An OAuth2TokenServiceRequest can be created and started from any thread.
-class OAuth2TokenServiceRequest : public OAuth2TokenService::Request,
-                                  public base::NonThreadSafe {
+class OAuth2TokenServiceRequest : public OAuth2TokenService::Request {
  public:
   class Core;
 
@@ -101,6 +100,8 @@ class OAuth2TokenServiceRequest : public OAuth2TokenService::Request,
   const std::string account_id_;
   scoped_refptr<Core> core_;
 
+  SEQUENCE_CHECKER(sequence_checker_);
+
   DISALLOW_COPY_AND_ASSIGN(OAuth2TokenServiceRequest);
 };